The present invention relates generally to devices and methods for repair of heart valves, such as annuloplasty rings and bands. More particularly, it relates to annuloplasty prostheses providing non-invasive valve status information following implant.
Annuloplasty prostheses, generally categorized as either annuloplasty rings or annuloplasty bands, are employed in conjunction with valvular reconstructive surgery to assist in the correction of heart valve defects such as stenosis and valvular insufficiency. There are two atrio-ventricular valves in the heart. The mitral valve is located on the left side of the heart, and the tricuspid valve located on the right side. Anatomically speaking, each valve type forms or defines a valve annulus and valve leaflets. To this end, the mitral and tricuspid valves differ significantly in anatomy. For example, the annulus of the mitral valve is somewhat “D” shaped, whereas the tricuspid valve annulus is more nearly circular.
Both valves can be subjected to or incur damage that requires the valve in question to be repaired or replaced. The effects of valvular dysfunction vary. For example, mitral regurgitation, a complication of end-stage cardiomyopathy, has more severe physiological consequences to a patient as compared to tricuspid valve regurgitation. Regardless, many of the defects are associated with dilatation of a valve annulus. This dilatation not only prevents competence of a valve, but also results in distortion of the normal shape of a valve orifice. Remodeling of an annulus is therefore central to most reconstructive procedures on a mitral valve. In this regard, clinical experience has shown that repair of a valve, when technically possible, produces better long-term results as compared to valve replacement.
Many procedures have been described to correct the pathology of the valve leaflets and their associated chordae tendinae and papillary muscles. For example, with respect to the mitral valve, it is a bicuspid valve having a large posterior leaflet that coapts or meets with a smaller anterior leaflet. The part of the mitral valve annulus that is attached to the anterior leaflet is called the anterior aspect, while the part attached to the posterior leaflet is called the posterior aspect. There are two fibrous trigones that nearly straddle the anterior aspect. With this in mind, in mitral repairs, it is considered important to preserve the normal distance between the two trigones. A significant surgical diminution of the inter-trigonal distance may cause left ventricular outflow obstruction. Thus, it is desirable to maintain the natural inter-trigonal distance during and following mitral valve repair surgery.
Consequently, when a mitral valve is repaired surgically, the result is generally a reduction of the size of the posterior aspect of the mitral valve annulus. As part of a typical mitral valve repair, an annulus or segment thereof (e.g., anterior or posterior aspect) is diminished (i.e., constricted) so that the leaflets may coapt correctly upon closing of the valve, or an annulus is stabilized to prevent post-operative dilatation from occurring, either as frequently achieved by implantation of a prosthetic ring or band in a supra annular position. The purpose of a ring or band is to restrict and/or support an annulus to correct and/or prevent valvular insufficiency. However, it is important not to overly restrict an annulus as an unacceptable valvular stenosis may result. In tricuspid valve repair, constriction of an annulus usually takes place by positioning a band partially about the posterior leaflet segment and a small portion of the adjacent anterior leaflet segment. The septal leaflet segment is not usually required to be shortened.
As described above, both annuloplasty rings and annuloplasty bands are available for repair of an atrio-ventricular valve. Examples of annuloplasty rings are shown in U.S. Pat. Nos. 5,306,296; 5,669,919; 5,716,397; and 6,159,240, the teachings of which are incorporated herein by reference. In general terms, annuloplasty rings completely encompass both the anterior and posterior aspects of a valve annulus, and have either a rigid (or semi-rigid) design, or a flexible design. Annuloplasty bands, on the other hand, are specifically designed to primarily encompass only a portion of the valve annulus. With the rigid or semi-rigid configuration, an annuloplasty ring serves to remodel the dysfunctional valve annulus to a desired shape such as that which would mimic the normal systolic shape of the valve. In this regard, and relative to the mitral valve, recent studies have identified that the healthy mitral valve annulus has a natural saddle shape that becomes exaggerated in systole. Efforts have been made to provide a rigid annuloplasty ring that more closely mimics this saddle shape, for example as shown in U.S. Pat. No. 6,858,039 and U.S. Publication No. 2003/0093148, the teachings of which are incorporated herein by reference. While viable, this remodeling/rigid annulus support may overtly restrict natural movement of the mitral valve annulus when functioning during diastole and systole, especially in the mitral valve anterior aspect as suggested by Parrish, L. M., et al., The Dynamic Anterior Mitral Annulus, (Annals. of Thoracic Surgery 2004; 78:1248-55). Further, once implanted, these and other conventional annuloplasty prosthesis do not provide a means for post-operative evaluation or monitoring of a shape of a repaired valve annulus.
Annuloplasty bands have been developed as an alternative to an annuloplasty ring. An annuloplasty band can have a rigid (or semi-rigid) design, or can be flexible. With the rigid or semi-rigid approach, an annuloplasty band serves to remodel a portion of a valve annulus, whereas other portions of a valve annulus to which an annuloplasty band is not applied are free to move or function in a more natural manner. Thus, for example, with respect to a mitral valve annulus, an annuloplasty band is implanted at the posterior aspect of the annulus; a majority or all of the anterior aspect is unencumbered by the annuloplasty band, and thus can function or move in a more natural manner. Examples of annuloplasty band designs are described in U.S. Pat. No. 6,786,924, as well as U.S. Pat. No. 5,824,066 and PCT International Patent Publication No. WO00/74603, the teachings of all of which are incorporated herein by reference. While highly viable, conventional annuloplasty band configurations again do not provide a surgeon with the ability to easily review a complete shape of the valve annulus or otherwise provide a subsequent indication that an annuloplasty band has been implanted (as opposed to an annuloplasty ring).
In light of the above, a need exists for annuloplasty prosthesis providing a more complete representation of the repaired valve annulus via non-invasive, post-operative procedures.